نشریه سنجش و ایمنی پرتو
پیاپی 2 (بهار 1392)

According to radiation protection regulations, microwave radiation intensity should not exceed general public exposure limit defined in "Iranian Standard-Non ionizing radiation-exposure limits". Based on this standard, exposure limit for microwave ovens, which work at 2450 MHz, is 1mW/cm2. By implementing such standard, about 575 imported ovens, including different models and brands were tested and categorized to four groups A, B, C, D based on the maximum microwave radiation around the oven. Microwave leakage for A, B, C groups were measured to be less than or equal to 0.1, 0.3, 0.5mW/cm2respectively but for group D was more than 0.5mW/cm2 .Result are presented and compared.

The aim of this paper is the examining ways for quality control and calibration of Rams-88 calibrator. The device measures the amount of &gamma and &beta rays in radio medicines by means of the amount of radioactivity of radio nuclide. In this paper experiments has been done for explaining correct operation of these devices using standard method including precision, accuracy and linearity of response and position sensitivity. Minimum errors resulted for precision, accuracy and linearity of response using standard method of IAEA-Tecdoc-602. The position sensitivity experiment was carried out by changing of source height in a holder of radioactive source in dose calibrator. An error of near %5 was resulted for the height of 0 - 4 cm, while the maximum error of about %30 was obtained for the height of 5 -10 cm.

Based on the last presented reports of UNSCEAR, inhalation of radon gas and its short-lived decay products is a major contributor to the human exposure from natural radioactivity. Lung cancer is the known effect on human health from exposure to radon in air. Radon is found in outdoor air of buildings of all kinds. The main important isotope of radon is 222Rn. Radon (222Rn) is a noble gas produced by radioactive decay of radium (226Ra), which is a decay product of Uranium (238U). Uranium and radium occur naturally in soils and rocks. Radon is found in significant concentrations in the human environment, particularly within indoor air of buildings faced by granite stones as internal decoration. Over the past few decades, natural radiation exposure due to 222Rn and its progeny inside houses has been recognized as a worldwide problem and a cause of significant lung cancer risk to the population .
In this study the results of measurement of activity concentration of radon in indoor air of two different buildings which have been used granite and carbonate stones as internal decoration, are presented and compared.
Activity concentration of radon was measured by AlphaGuardTM apparatus. The average radon concentrations determined in two different buildings with carbonates and granite stones were 11 and 59 Bq.m-3, respectively. These values are below the radon reference levels which range from 200-600 Bq.m-3 as recommended by ICRP, IAEA, and is lower than US-EPA and WHO action levels 148 and 100 Bq.m-3, respectively.

The development of a graphite ionization chamber in Iran is reported for first time, using graphite coatings collecting electrodes and guard rings. Its sensitive volume is about 200cm³, with a shape of a ring which is different from its older equivalents and a 7cm central hole that allows the passage of the direct radiation beam without attenuation. This kind of ionization chamber has already been designed with aluminum electrodes in IPEN (institute de pesquisas energetic as e nucleares, Brazil), however in the present model, the whole of the inside part of the ionization chamber is coated with graphite instead of aluminum. By changing the electrode material from aluminum to a graphite coating, an improvement in action of ionization chamber response in pre-operational tests such as stability, saturation curve, repeatability, polarity effect, linearity response and calibration is expected, which is in accordance with the international recommendations.

Basically Iran laws and regulations on the safety of nuclear installations were inspired by the respected international rules and norms, while in some cases there exist differences, the contents of most of these regulations are those of IAEA documents relating to safety of nuclear installations. In the mean time, the current laws and regulations of Iran on nuclear safety installations are not comprehensive, complete and sufficient. By comparatively analysis of Iran nuclear safety laws and regulations with those of IAEA, this article tries to clarify, describe and analyze current legal order of Iran in relation to nuclear installations safety and their compatibility with the established international norms .

Thallium doped calcium fluoride (CaF2:Tl) nanoparticles were produced for the first time by using the hydrothermal method. X-ray diffraction (XRD) and scanning electron microscope (SEM) were utilized to analyze the synthesized material. The particle size of about 45 nm was evaluated using XRD data which was supported by the SEM images. Thermoluminescence glow curve of this nanophosphor exhibits three overlapping glow peaks at 433, 466 and 505◦ K. The optimum concentration of activator was found at 1 mol% for TL responses relative to gamma rays of 60Co.The prepared nanoparticles exhibit a linear dose response up to 1000 Gy absorbed dose relative to gamma rays of 60Co source. Other dosimetric features of this novel phosphor are also presented and discussed.

As public concern mounts over exposures to ionizing radiation stemming from environmental releases of radionuclides following nuclear accidents, there is a growing need to develop reliable techniques that reconstruct exposures and doses to individuals. Especially in situations where conventional dosimeters were not in place at the time of facing to radiation exposure. In order to provide guidance for emergency situations as well as implementing midterm measures, retrospective dosimetry is defined as the process of estimating doses to individuals from past exposures to ionizing radiations. Joined-up approaches have been introduced for this purpose in biological and physical dosimetry. Main techniques includebiological dosimetry, electron paramagnetic resonance dosimetry and luminescence dosimetry. This project has been devoted to the evaluation of potentials and limitations of these techniques and an experimental assessment of the feasibility of using TL properties of electronic components from personal objects such as mobile phones for retrospective dosimetry. We studied luminescence properties of electronic components inside conventional mobile phones like capacitator, resistor and inductor experimentally. Previous studies have shown alumina inside electronic components of portable electrical tools is a suitable material for luminescence dosimetry. Our analysis of recorded glow curves reveals that among the electronic components found in available mobile phones, alumina richconductors seem particularly suitable for retrospective dosimetry using thermoluminescence, and shows the potential of conventional TL equipment for such purposes.